1. Field of the Invention
This invention relates to a foamable silicone rubber composition, and more particularly to a foamable silicone rubber composition capable of obtaining a foam with a superior strength.
2. Description of the Prior Art
Methods in which organopolysiloxane compositions foamable at room temperature or by heating to a slightly higher temperature are used have been hitherto proposed as methods for obtaining silicone rubber foams useful as foams, fillers, sealing materials, etc. for use in construction. Known compositions include, for example, a composition in which an organosiloxane having a silicon-bonded hydrogen atom and an organosilane having a silicon-bonded hydrogen atom are subjected to dehydrogenation reaction in the presence of a dehydrogenation catalyst such as a quaternary ammonium salt, a heavy metal carboxylic acid salt or an alkali metal alkoxide (Japanese Patent Publication (KOKOKU) No. 9297/1958 and No. 8755/1969), and a composition in which an organosiloxane having a silicon-bonded hydrogen atom is reacted with an organosilane having a silicon-bonded hydroxyl group in the presence of a platinum compound (Japanese Patent Publication (KOKOKU) No. 12675/1970, No. 42826/1977 and No. 23462/1981, and Japanese Unexamined Patent Publication (KOKAI) No. 196330/1984).
All the silicone rubber foams obtained from these compositions, however, have a lower strength because of their relatively large cells in the foams, so that they have been not necessarily suited as the sealing materials or fillers for use in construction.